Heretofore, it has been practiced to print the articles, which are delivered as an electronic document, as a hard copy for reading, however, in recent years, a display element, which enables reading without printing a hard copy, has been desired because an increasing volume of articles are delivered due to popularization of intranet and internet or increase of transmission speed.
As these display elements for reading, there is a CRT, a liquid crystal display or an organic EL display. However, these displays cause significant fatigue because of humane technological reasons due to being emission types and are pointed out not to withstand reading for a long time. Further, there is a disadvantage that a reading place is limited to places where a computer can be installed.
To overcome these disadvantages, recently proposed are a reflection type display which is so-called a paper like display or an electronic paper, and primarily includes such as a method to transfer colored particles between electrodes by electrophoresis (for example, refer to patent literature 1), a method to rotate a particles provided with dichroism by a magnetic field (for example, refer to patent literature 2), or an electrochromic display element which utilizes a redox reaction of a metal ion (for example, refer to patent literatures 3 and 4).
Among these, in an electrochromic display element, which utilizes a redox reaction of a metal ion, there are proposed one provided with a white reflective plate on the back surface (for example, refer to patent literature 5) and one in which a colorant is incorporated into polymer solid electrolyte to increase the whiteness (for example, refer to patent literature 6). However, they cannot be said sufficient as whiteness against human vision.
[Patent Literature 1] U.S. Pat. No. 6,120,588
[Patent Literature 2] U.S. Pat. No. 5,754,332
[Patent Literature 3] JP-A No. 10-133236 (Hereinafter, JP-A refers to Japanese Patent Publication Open to Public Inspection)
[Patent Literature 4] JP-A No. 10-148851
[Patent Literature 5] JP-A No. 11-101994
[Patent Literature 6] JP-A No. 2002-258327
The present invention has been made in view of the above problems, and an objective of this invention is to provide a display element, a display apparatus and a manufacturing method thereof, employing a display material in which the whiteness of the background is sufficiently increased as visional characteristics and which performs color change by an electrochemical redox reaction.